Concentrated Reef Builder for Coralline Algae, Corals, Clams & other Marine Invertebrates Overview Complete source of the elements and molecules that are directly used by corals, clams, and other reef-building invertebrates and organisms to create skeletal material and grow. Provides calcium (140,000 ppm), strontium, magnesium, and potassium in approximately the same ratios* in which they occur in aragonite. Very strong source of carbonates (derived from aragonite). Increases alkalinity to help stabilize pH. Stronger than competing products. May be used as an inexpensive alternative to automated calcium reactor systems Free of phosphate, silicate, and organic material.